1. Technical Field
The present invention relates to network repeaters, more specifically to an IEEE 802.3 compliant repeater providing a bridge between two media domains.
2. Background Art
Network repeaters are typically used as a bridge between network nodes, for example network stations serving as data terminal equipment (DTE) on different network media. Repeaters provide the advantage of extending the physical distance between network nodes by receiving a data packet from one network media, reconditioning the physical signal, and outputting the data packet to a second network media. The repeater may also forward carrier sense and collision signals, effectively extending the collision domain of one media on to the second media.
Repeaters interconnecting network nodes on different network media have conventionally been configured to connect only networks operating at the same transmission rate. Hence, a repeater would conventionally connect a 10 Mb/s network media to another 10 Mb/s network media, or a 100 Mb/s network media to another 100 Mb/s network media. If the repeater was used to connect the media of two different networks operating at different network speeds, the repeater would require substantially large buffering in order to accommodate the difference in transmission rates without loss of data packets.
There is a need for an arrangement for interconnecting different speed packet switched networks using a repeater, without the necessity of substantially large buffering.
There is also a need for a network repeater configured for interconnecting different speed networks that selectively controls transmission of data packets between the networks to reduce the necessity of large buffers without losing data packets.
These and other advantages are attained by the present invention, where a filter selectively outputs a data packet received from one network media domain to another network media domain, having a slower transmission rate, based on the destination address specified in the received data packet.
According to one aspect of the present invention, a network repeater comprises first network ports, each configured for outputting a first received data packet to the remaining first network ports, the first network ports sharing a first media domain having a first transmission rate, second network ports, each configured for outputting a second received data packet to the first network ports and the remaining second network ports, the second network ports sharing a second media domain having a second transmission rate less than the first transmission rate, and a filter selectively outputting the first received data packet to the second network ports for transmission on the second media domain based on a destination address specified in the first received data packet. Use of the filter to selectively output the first received data packet to the second network ports enables the first and second media domains to be connected without causing congestion on the second network port. Moreover, the selective output minimizes the amount of buffering necessary between the first and second media domain.
Another aspect of the present invention provides a method in a network repeater including the steps of receiving in a first network port a first data packet from a first media having a first transmission rate, supplying the first data packet to a second network port, coupled to a second media having a second transmission rate greater than the first transmission rate, for transmission on the second media, receiving in the second network port a second data packet from the second media, determining if the second data packet includes a destination address value specifying transmission of the second data packet to at least one network node in communication with the first media, and selectively supplying the second data packet to the first network port for transmission on the first media based on the destination address value determined as specifying transmission to the at least one network node. The determination of whether the second data packet is to be transmitted to the network node on the first media based on the destination address value ensures that data packets transmitted on the first media are not unnecessarily transmitted on the first media. Hence, the collision domains of the first and second media can be connected without substantial buffering within the repeater and without overwhelming the first media, even though the second media operates at a data rate faster than the first media.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.